Nortel Networks NTRN10AN, 3500 manual See Note

2-98Operation, administration, and maintenance (OAM) features

If congestion should occur at the destination storage device, it would begin withholding R_RDYs from the egress OPTera Metro 3500. All transmitted Fibre Channel frames are buffered in the egress OPTera Metro 3500 card memory. When a certain memory threshold is reached, a flow control signal is sent to the ingress OPTera Metro 3500 to stop the transmission of Fibre Channel frames. Upon receipt of these flow control messages, the ingress OPTera Metro 3500 would in turn withhold R_RDYs from the source storage device. This mechanism ensures that downward pressure is cascaded upstream to the source of the traffic until congestion abates.

Table 2-20 on page 2-98, lists the sample distances based on the available WAN bandwidth.

Table 2-20

Fibre Channel extended reach sample distances

STS1-nv	Round Trip Delay	Distance	STS3c-nv	Round Trip Delay	Distance
	(∝s)	(kms)		(∝s)	(kms)
	See Note 1	See Note 2			See Note 2
19	9870	987	6	9870	987
See Note 3			See Note 3
18	10160	1016	5	11820	1182
17	10760	1076	4	14770	1477
			See Note 3
16	11430	1143	3	19690	1969
15	12190	1219	2	29540	2954
14	13060	1306	1	59080	5908
			See Note 3
13	14070	1407
12	15240	1524
11	16620	1662
10	18290	1829
9	20320	2032
8	22860	2286
7	26120	2612
6	30480	3048
5	36570	3657
4	45710	4571

OPTera Metro 3500 Multiservice Platform NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004